Electrolytic alkali halogen cells



Feb. 20, 1945. STUART 2,370,087

ELECTROLYTIC ALKALI HALOGEN CELLS Original Fild Sept. 4, 1940 4 Sheets-Sheet 1'.

INVENTOR Feb. 20, 1945. K. E. STUART 2,370,087

ELECTROLYTIC ALKALI HALOGEN CELLS Original Filed Sept. 4, 1940 4 Sheets-Sheet 2 INVENTOR Feb. 2Q, 1945. K. E. STUART ELECTROLYTIC ALKALI HALOGEN CELLS 4 Sheets-Sheet 5 Original Filed Sept. 4, 1940 I I "I! .INVENTOR Feb. 20, 1945. K, E STUART 2,370,087

ELECTROLYTIC ALKALI HALOGEN CELLS Original Filed Sept. 4, 1940 4 Sheets$heet 4 INVENTOR.

atented Feb. 20, 1945 UNITED STATES PATENT, OFFICE 2,370,087 ELECTROLYTIC ALKALI HALOGEN CELLS Kenneth E. Stuart, Niagara Falls, N. Y., assignor to Hooker Electrochemical Company, Niagara Falls, N. Y., a corporation of New York Original application September 4, 1940, Serial No. 355,317. Divided and this application April 17, 1941, Serial No. 389,033

6 Claims. (Cl. 204-266) My invention relates more particularly to an trodes are perpendicular is a clearance or pasalkali chlorine cell for production of caustic sage I3. Each bank of cathodic electrode is conalkali, chlorine and hydrogen from alkali metal ductively joined to the side wall of tank I to which chlorides. it is adjacent by a strip of foraminous metal simi- My invention is a modification of the cell dislar to that from which the electrodes themselves closed in PatentNo. 1,866,065, granted to me July are formed. Each bank of cathodic electrode 5, 1932. One obJect of my invention is to provide members extends downwardly to the bottom of a means for securely and conductively afllxing tank I and is conductively joined thereto. elongated graphite anodes to a metal plate by one. 4 The form of these cathodic electrode members end with a minimum of sacrific of graphite. An- 10 will be better understood by reference to Figs. 4 other object of my invention is conductively to and 5, which illustrate one method of constructaffix foraminous metal cathodic electrode eleing these members. A long sheet of foraminous ments to their housing structure so as to afford metal, preferably steel wire screen, having'a width improved electrical conductivity from'the struc- .slightly greater than the height of the finished ture to the electrodes. electrode members. is first bent into wide corru- Refernngto the drawings: gations separated by narrow corrugations. The Fig. l is a plan view of my cell, partly cut away wide corrugations are of a width equal to the disto show the interior construction. tance which is to separate the finished active Fig. 2 is a side elevation of my cell in section cathodic electrode surfaces, between which suralong line ca of Fig.1. faces the anodic electrodes are later to be in- Fig. 3 is an end elevation of my cell, in section stalled, clearance being provided between the along line bb of Fig. 1. anodic and cathodic electrode surfaces for circu- Figs. 4 and 5 are perspective views of a number lation of the electrolyte. The narrow corrugaof cathodic electrode elements, illustrating one tions are of a suflicient width to provide passages method of constructing and assembling them. between the active cathodic electrode surfaces for Fig. 6 is a sectional elevation of aportion of the removal of hydrogen and liquid products resultcell corresponding to that of Fig. 2, but illustratin: fr m the hydrolysis. The edges of the maring a modified detail of construction. row corrugations at one side of the sheet are then Fig. '7 is a sectional elevation of a modification Deemed toward each other, preferably over a semiof the cell of my Patent No. 1,866,065, above recircular mandrel, until they meet in seam I6, ferred to, illustrating an application thereto of where theyare butted and welded. The screen certain features of my present invention, is also peened outward at the roots of the narrow Referring tothe figures: corrugations as illustrated at ll, Fig. 4.- A strip My cell comprises a cathode assembly forming a of e Screen s s l p d 8 e e the liquid tight base member and an anode assembly other e being left straight. A portion of such r i pon andmaking, a liquid tight joint a strip is illustrated at is, Fig. 5. The radii and therewith. pitch of these scallops are those of the peened The cathode assembly comprise a, rectangular roots l7. These strips are butted and welded container or tank I, preferably of steel, housing along the scallops to roots I! of the cathodic electhe cathodic electrode structure. The bottom of trode members II. The number of cathodic elec-' tank I is reinforced byribs 4, extending transtrode members II formed and assembled in this versely of the cell, and staggered ribs 5, 8 and 1, way depends upo ';.;t; he current under which the 8 extending longitudinally of the cell. Pad 9 cell is designedto crate and otherpracticalconand II) completethree points of support upon slderatmnswhich the cell may rest upon insulators (not A supp structure f t e cathodic elecshown) supported from the floor. trode members is then built into tank I. This The active surface of the cathode assembly support is made up of a number of uprigh steel consists of a series of thin, flat, foraminous cathbars, 23. These are of a width to slide freely 1M0 odic electrode members II, set on edge, and hence. the clearances between cathodic electrode memwith their flat faces vertical. These cathodic bers II, but eve theless wide enough to support electrode members are adapted to alternate with he Walls f these clearances against collaps n the anodic electrodes, to be described later. In p essu a s 23 r weld d y t ir l w nds the preferred embodiment of the invention, they to the bottom of tank I. They are arranged in are parallel with each other and arranged in rows, preferably six;;,;and spaced at exactly the groups or banks. The members of each group distance which'is. ntended to be the pitch of are perpendicular to a. side wall of tank I. Be-- the electrode members or distance between their tween the two banks is a clearance or passage I2, corresponding parts. At the ends of the cell bars to facilitate circulation'of electrolyte (see Figs. 1 23 are supported from therend wall by legs 21. and 3). Between each bank of cathodic electrode Flat steel bars 28 are also welded around the four members and the side wall to which the elec- (0 sides of the cell near its rim, forming a shelf.

Two banks of cathode electrode assemblies, formed as above described, are then inserted in the tank with their lower edges resting on the bottom of the tank, their borders, formed by strips I8, overlapping shelf 28 and their convolutions accurately spaced by upright bars 23. In this position, the borders are welded to the side walls and the lower edges to the bottom of tank i. Strips I8 are continued around the ends of the tank by strip 20 and the sheets forming the convolutions are brought together, butted and welded at the ends of the cell. There is thus completed a cathode assembly comprising imperforate outer walls and bottom and a perforate corrugated inner structure.

The cathodic electrode members I I and, in fact, all of the foraminous cathode structures, are covered with a permeable diaphragm, as indicated by the speckled surfaces, dividing the cell into anode and cathode compartments. This is preferably of asbestos fiber. It will be noted that the cathodic electrode members comprise surfaces that could not be covered by a sheet of paper. The diaphragm can therefore best be applied by the method disclosed in my U. S. patents, Nos. 1,855,497; 1,862,244 and 1,865,152. The diaphragm formed in this way will cover strips I8 and 20, extending along the sides and ends of the cell respectively, and will therefore have its outer edges overlapped and ealed by the anode assembly, to be described later, which forms a cover to the cell. The imperforate bottom of tank I will however, remain uncovered and this must be insulated, otherwise caustic alkali would be formed here and as this would be on the anode side of the diaphragm it would come into con-' tact with chlorine and be converted to the corresponding chlorate, with consequent loss of efiiciency. Ordinarily it is very difficult to insulate imperforate metal and to protect diaphragm edges within such a cell. In the present case, however, this becomes a very simple matter. Since all the imperforate metal is in the bottom of tank I and the lower diaphragm edges are contiguous thereto, all that is necessary is to pour in grout or molten bituminous material, or both, as illustrated at 29, Fig. 2. This will spread uniformly over the surface to be protected and will be firmly anchored by the screen and its convolutions.

The anode assembly comprises a rectangular frame and cover plate 33, supporting. a series of graphite anodic electrodes 3I. The proportion and dimensions of frame 30 conform to the rim of tank I so that this frame is adapted to rest upon shelf 28. Frame 30 is of non-conducting material, such as wood, slate, composition of. cement and asbestos, etc. Cover 33 is bolted to frame 30 as shown. On the under surface of cover 33 are a number of flat steel fins 36, Fig. 2. These are welded by. their edges to cover 33 and are spaced so that one fln 36 comes midway be tween each pair of rows of anodic electrodes 3I. Holes 36b are drilled at intervals through fins 36. Holes 3Ib are likewise drilled through graphite anode blades 3| near their upper ends. The upper ends of these blades are also notched, as shown at 31. With the plate inverted and the graphite blades held in position in a jig, a slab 33 of low melting metal or alloy, preferably lead, is formed, embedding not only fins 36, but the ends of graphite blades 3|. This is done by introducing the metal while molten. The molten metal flows through the holes in fins 36 and through the holes and notches in graphite blades 3 I, thus anchoring the latter firmly to the former. Before pouring in the molten metal the under surface of cover 33 is tinned. The lead bonds with the tinned surface, thus ensuring good electrical contact.

The inner surfaces of cover 33 and lead slab 35 are protected against electrolysis by a layer 38, preferably of bitumen or asphalt. This likewise is poured in while molten and flows through the notches between contiguous blades. When the anode assembly is in place and frame 30 resting upon shelf 28 the joint between it and the cathode assembly is sealed by pouring in bitumen 39.

Cover 33 may be reinforced by steel frame 32 of angle section, to stiffen it against warping when the molten lead is poured. in contact with its opposite side.

At a oint above passage I2, preferably above the geometrical center of the cell, an exit 40 is provided for chlorine. This comprises a section of ceramic pipe 4| in an envelope 42 of steel, the bitumen of non-conducting layer 38 being allowed to fill the space between. Between the upper edges of cathodic electrode members II and the lower surface of non-conducting layer 38 sufficient clearance is provided for circulation of electrolyte and to permit the chlorine liberated on anodic electrodes 3| to find its way to passages I2 and thence to exit 43. I

Hydrogen liberated on the cathodic side of the diaphragm finds its way through passage I3 to exit 44.

The liquid products of electrolysis, together with undecomposed electrolyte, are discharged from the cathode compartment through pipe 45 which, although connected to tank I near its bottom, is preferably formed with a high point slightly below the level of the upper edge of cathodic electrodes II, so that the cathode compart ment of the cell is normally nearly filled with liquid.

Electrolyte may be supplied to the cell in the form of a jet (not shown) directed downwardlyv into chlorine exit 43. The level of the electrolyte within the cell above the lower surface of layer 38 is indicated by liquid column "in manometer 49 in response to gas pressure built u in chamber 48 by chlorine evolved upon the anodes beneath chamber 48 and trapped therein under'the hydrostatic head corresponding to the depth of submergence of the mouth of the chamber, as described in co-pending application Serial No. 304,813, filed by me November 16, 1939.

Bus bar 34 is bolted'and soldered to the upper surface of cover 33 (passing through an opening in frame 32). Bus bar 36 is similarly bolted and soldered to the end of tank I. These two bus bars serlve to complete the electrical connections to the ce Fig. 6 illustrates a modified construction in which lead slab 35 is dispensed with. In this case,

the ends of the anode blades are coated, as with copper, zinc or tin, by electroplating or dipping, and under surface of plate 33 is tinned or galvanized as before, and the anode blades are butted against and bonded directly to plate 33. A layer of grout 50 may then be applied, to increase the mechanical strength of the support. This may beprotected by a layer of bitumen 38. In this way the proportional. inactive graphite may be reduced to an absolute minimum.

In the construction of Fig. 2, obviously the layer of lead between the ends of the anode blade I the metallic surfaces-between anode assembly comprising an;

and plate 33 could be dispensed with and the blade butted directly against the plate as in Fig. 6.

Fig. '7 is a sectional elevation of a modification of the cell illustrated and described in my U. S. Patent No. 1,866,065 above referred to. In this case the anode assembly is similar to that above described, but inverted, plate 33aserving as a bottom closure, instead-of'as the cover, for the cell, analogous parts being indicated by the same reference figures, followed by the suffix a. Thus, this assembly comprises anodes 3la, provided with holes 3Iba, an insulating frame 30a, steel plate 33a, lead slab 35a, fins 36a, provided with holes 366a, and bitumen layer 380.. A gasket 5| is interposed between-frame 30a and plate'33a.

,A cathode assembly la, provided with cathodic electrodes Ha, is supported .by frame 300, with gasket 53 between, and a concrete cover 52 rests upon the cathode assembly, with gasket 54 be tween. Bus bars 3'4a'and 46a serve to complete the electrical connections to the anode and cathode assembly respectively. 55 is a tube through which a jet of electrolyte is supplied to the cell.

While I have illustrated and described one method of forming the cathodic electrodes and two methods of afiixing the graphite anode blades to the steel cover of the cell I do not wish to be limited thereto. as other equivalent methods of accomplishing these objectives will suggest themselves to persons skilled in the art.

This application is a division of application Serial No. 355,317, filed September 4, 1940.

I claim as my invention:

1. In an electrolytic alkali chlorine cell, an anode assembly comprising a fiat, normally level frame structure and a cover plate therefore adapted to carry the cell current and constructed of rigid, rolledsheet, structural metal; a plurality of spaced, aligned, straight, elongated, graphitic electrodes extending perpendicularly with respect to said plate and mechanically and conductively afflxed by one'end thereto, said plate .constituting a fluid-retaining closure for said to said plate and mechanically and conductively afllxed by one end thereto through a relatively low-melting metallic medium firmly anchored to.

said electrodes and'making a solder-type bond with the inner surface of said plate. 'saidplate constituting a fluid-retaining closure forg'said' structure over the entire horlzontalarea enclosing said electrodes; .and' impervious.- n' g ducting, chlorine-resistant material 3. Inan ,electrolyticbalhali;

frame structure and a cover plate" therefore adapted to carry the cell current and of rigid, rolled sheet, structural metal. coated on its inner surface witha relatively low-melting metal bonded thereto; a plurality of spaced,-

iii

aligned, straight, elongated, graphitic electrodes having one of their ends square with their axes and metal coated, said electrodes extending perpendicularly with respect to said plate with-their metal coated ends butted against and mechanically and conductively afiixed tothe inner surface thereof through a relatively low-melting metallic medium making asolder-type bond with he metal coating of said plate and electrode ends,

said plate constituting a fluid-retaining closure for said structure over the entire horizontal area enclosing said electrodes; and impervious, nonconducting, chlorineresistant material protecting the metallic surfaces between said electrodes.

4. In an electrolytic alkali chlorine cell, an anode assembly comprising a fiat, normally level frame structure and 'a cover plate therefore adapted to carry the cell current and constructed of rigid, rolled sheet, structural metal, coated on its inner surfacewith a relatively low-melting metal bonded thereto; a plurality of spaced, aligned, straight, elongated, graphitic electrodes having one of their ends square with their axes and electroplated, said electrodes extending per-- pendicularly with respect to said plate with their electroplated ends butted against and mechanically and conductively afilxedto the inner sur-.

face thereof through a relatively low-melting metallic medium making a solder-type bond with the metalv coating of said plate and electroplate of said ends, said plate constituting a fluid-retaining closure for said structure over the entire horizontal area enclosing said electrodes; and

impervious, non-conducting, chlorine-resistant material protecting the metallic surfaces between .said electrodes.

5. In an electrolytic alkali chlorine cell, an anode assembly comprising a fiat, normally level frame structure and a cover plate therefore adapted .to carry the cell current and constructed of rigid, rolled sheet, structural metal; a plurality of spaced, aligned, straight, elongated, graphitic electrodes extending perpendicularly with respect to said plate and having one oftheir ends embedded in a slab of relatively low-melting metal soldered to the inner surface of said plate, said plate constituting a fluid-retaining closure forsaid structure over the entire horizontal area enclosing said electrodes; and impervious, non-conducting, chlorine-resistant material protecting the metallic surfaces between said electrodes.

.6. In an' electrolytic alkali chlorine cell. an anode assembly comprising a fiat, normally level frame structure and a cover plate therefore adapted to carry the cell current and constructed of rigid, rolled sheet, structural metal; parallel rows of spaced, aligned. straight, elongated,

graphitic electrodes, having holes therethrough nearone end, extending perpendicularly with respect'to said plate and having one of their ends embedded in a slab of relatively low-melting metal beyond the depth of said holes; fins having holes therethrough fixed to said plate between said rows and com letely embedded in said slab;

. said plate constituting a iluld retaining closure for said structure over the entire horizontal area enclosingsaid electrodes; and impervious, nonconducting, chlorine-:reslstant material Pl'Qtecting the metallic riaces between said electrodes. I 7 a. similar. 

